München 2019 – wissenschaftliches Programm

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AGPhil: Arbeitsgruppe Philosophie der Physik

AGPhil 3: Philosophy of Cosmology III

AGPhil 3.2: Vortrag

Dienstag, 19. März 2019, 11:45–12:15, HS 10

Some Issues and Non-Issues in Concordance Cosmology — •Marc Holman — University of Western Ontario

The so-called “flatness problem” is widely taken to be a major outstanding problem of modern cosmology and as such forms one of the prime motivations behind inflationary models. Upon distinguishing three different versions of this putative problem, I show that the observational fact that the large-scale Universe is so nearly flat is ultimately no more puzzling than similar “anthropic coincidences”, such as the specific (orders of magnitude of the) values of the gravitational and electromagnetic coupling constants. In particular, there is no fine-tuning problem in connection to flatness of the kind usually argued for. Furthermore, the arguments regarding flatness and particle horizons typically found in cosmological discourses in fact address a mere single issue underlying the standard FLRW cosmologies, namely the extreme improbability of these models with respect to any “reasonable measure” on the “space of all spacetimes”. In other words, there is arguably a serious cosmological fine-tuning problem, but it pertains to generic FLRW geometries. By their very nature, dynamical mechanisms such as inflation are inapt for addressing this latter problem.